docs: def set_volume(self, volume):
          """Set a new volume level."""
          if volume > 100 or volume < 0:
              raise Exception('Bad request to volume control. '
                              'Must be between 0 and 100')
          params = ('<InstanceID>0</InstanceID><Channel>Master</Channel>'
                    '<DesiredVolume>{}</DesiredVolume>').format(volume)
          self.soap_request(URL_CONTROL_DMR, URN_RENDERING_CONTROL,
                            'SetVolume', params)